Methods of attaching a polycrystalline diamond compact to a substrate

ABSTRACT

Methods of attaching a polycrystalline diamond compact (PDC) element to a substrate include maintaining a gap between the PDC element and an adjacent substrate, and at least substantially filling the gap with a deposition process. Methods of forming a cutting element for an earth-boring tool include forming a PDC element by pressing diamond crystals together, forming a substrate including a particulate carbide material and a matrix material, leaving a gap between at least portions of the PDC element and the substrate, masking surfaces of the PDC element and of the substrate that do not face the gap, and forming an adhesion material on surfaces of the PDC element and of the substrate that face the gap. Cutting elements for earth-boring tools include a PDC element attached to a substrate with at least one of diamond, diamond-like carbon, a carbide material, a nitride material, and a cubic boron nitride material.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional PatentApplication Ser. No. 61/535,618, filed Sep. 16, 2011, the disclosure ofwhich is hereby incorporated herein in its entirety by this reference.

TECHNICAL FIELD

Embodiments of the present disclosure relate generally to methods ofattaching a polycrystalline diamond compact (“PDC”) to a substrate.Embodiments relate to methods of attaching a PDC to a substrateincluding depositing material between the PDC and the substrate by adeposition process. Embodiments of the disclosure relate to cuttingelements formed using such methods. Embodiments of the disclosure alsorelate to earth-boring tools formed using such methods.

BACKGROUND

Earth-boring tools for forming wellbores in subterranean earthformations generally include a plurality of cutting elements secured toa body. For example, fixed-cutter earth-boring rotary drill bits (alsoreferred to as “drag bits”) include a plurality of cutting elements thatare fixedly attached to a bit body of the drill bit. Similarly, rollercone earth-boring rotary drill bits may include cones that are mountedon bearing pins extending from legs of a bit body such that each cone iscapable of rotating about the bearing pin on which it is mounted. Aplurality of cutting elements may be mounted to each cone of the drillbit.

The cutting elements used in such earth-boring tools often includepolycrystalline diamond compact (often referred to as “PDC”) cuttingelements, which are cutting elements that include cutting faces of apolycrystalline diamond material. Polycrystalline diamond material ismaterial that includes inter-bonded grains or crystals of diamondmaterial. In other words, polycrystalline diamond material includesdirect, inter-granular bonds between the grains or crystals of diamondmaterial. The terms “grain” and “crystal” are used synonymously andinterchangeably herein.

Polycrystalline diamond compact cutting elements are formed by sinteringand bonding together relatively small diamond grains under conditions ofhigh temperature and high pressure in the presence of a metal solventcatalyst (such as, for example, cobalt, iron, nickel, or alloys andmixtures thereof) to form a layer or “table” of polycrystalline diamondmaterial on a cutting element substrate. These processes are oftenreferred to as “high temperature/high pressure” (or “HTHP”) processes.The cutting element substrate may comprise a cement material (i.e., aceramic-metal composite material) such as, for example, cobalt-cementedtungsten carbide. In such instances, the cobalt (or other catalystmaterial) in the cutting element substrate may be swept into the diamondgrains during sintering and serve as a catalyst material for forming theinter-granular diamond-to-diamond bonds between, and the resultingdiamond table from, the diamond grains. In other methods, powderedcatalyst material may be mixed with the diamond grains prior tosintering the grains together in an HTHP process.

Upon formation of a diamond table using an HTHP process, catalystmaterial may remain in interstitial spaces between the grains of diamondin the resulting polycrystalline diamond table.

Differences in the thermal expansion between the diamond table and thecutting element substrate to which it is bonded may result in relativelylarge compressive and/or tensile stresses at an interface between thediamond table and the substrate that eventually lead to deterioration ofthe diamond table, cause the diamond table to delaminate from thesubstrate, or result in general ineffectiveness of the cutting element.

There are several conventional ways of making a PDC cutting element. Forexample, as shown in FIG. 1, a single HTHP cycle (e.g., in a diamondpress 25) may be used to press diamond feed 10 (e.g., polycrystallinediamond grit bound together in a matrix) and a carbide substrate 20together. The HTHP cycle simultaneously binds the material of the PDCfeed 10 together to form a PDC table 30 and binds the PDC table 30 tothe carbide substrate 20 to form a PDC cutting element 40. In anotherexample, shown in FIG. 2, diamond feed 10 may be pressed in an HTHPcycle (e.g., in a diamond press 25) to form a preformed PDC table 50.The preformed PDC table 50 may then be attached to a carbide substrate20 in another HTHP cycle (e.g., in a diamond press 25) to form a PDCcutting element 60. In either of the first two examples (FIGS. 1 and 2),the PDC table 30, 50 may include a cobalt (or other metal) catalyst andthe carbide substrate 20 may include cobalt (or other metal) in a matrixphase. Thus, the PDC table 30, 50 and the carbide substrate 20 may bebound together by cobalt (or other metal) at the interface between thePDC table 30, 50 and the carbide substrate. In yet another example,shown in FIG. 3, a preformed PDC table 50 may be formed by pressingdiamond feed 10 in an HTHP cycle (e.g., in a diamond press 25). Thepreformed PDC table 50 may be attached to a carbide substrate 20 by hightemperature brazing to form a brazed PDC cutting element 70. The PDCtable 50 and the carbide substrate 20 may be bound together by a brazealloy.

Conventional methods of attaching a PDC to a substrate, such as thosedescribed with reference to FIGS. 1-3, may have certain disadvantages.For example, stress may be induced at an interface between the PDC andthe substrate during the pressing cycle. Stress may also be induced atthe interface due to the high temperature of a brazing process. Thelevel of stress at the interface that is ideal for stress propagationwhen the PDC cutting element is used (e.g., in boring the earth) may notbe ideal for reducing the stress state after the pressing or brazingcycles.

Conventionally, PDC cutting elements including a PDC table and a carbidesubstrate are formed as described and then attached to the surface of abit body of an earth-boring tool. The PDC cutting elements may beattached to the bit body using a brazing process. The brazing processcan cause thermal stress or degradation of materials at the interfacebetween the PDC cutting elements and the bit body.

BRIEF SUMMARY

In some embodiments, the present disclosure includes methods ofattaching a polycrystalline diamond compact (PDC) element to asubstrate. In accordance with such methods, a PDC element is positionedadjacent to a substrate and a gap is maintained between the PDC elementand the substrate. The gap is at least substantially filled with anadhesion material using at least one of a chemical vapor depositionprocess, a plasma deposition process, a plasma-enhanced chemical vapordeposition process, a plasma arc deposition process, and a physicalvapor deposition process.

In some embodiments, the present disclosure includes methods of forminga cutting element for an earth-boring tool. In accordance with suchmethods, a PDC element is formed by pressing diamond crystals togetherand a substrate is formed, the substrate comprising a particulatecarbide material and a matrix material. The PDC element is positionedadjacent the substrate leaving a gap between at least portions of thePDC element and the substrate. Surfaces of the PDC element and of thesubstrate that do not face the gap are masked. An adhesion material isframed on surfaces of the PDC element and of the substrate that face thegap to at least substantially fill the gap with the adhesion material.

In some embodiments, the present disclosure includes cutting elementsfor an earth-boring tool. The cutting elements include a PDC elementattached to a substrate with an adhesion material, the adhesion materialformed by a deposition process and comprising at least one of diamond,diamond-like carbon, a carbide material, a nitride material, and a cubicboron nitride material.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a known method for forming a polycrystalline diamondcompact (“PDC”) cutting element.

FIG. 2 illustrates another known method for forming a PDC cuttingelement.

FIG. 3 illustrates yet another known method for forming a PDC cuttingelement.

FIGS. 4A-4C illustrate an embodiment of a method of the presentdisclosure for forming a PDC cutting element.

FIG. 5 is a side view of a PDC cutting element according to anembodiment of the present disclosure.

FIG. 6 is a side view showing details of a PDC element and a substrateto be attached to each other to form a PDC cutting element according toan embodiment of the present disclosure.

FIG. 7 is a perspective view of a drill bit formed according to anembodiment of the present disclosure.

FIG. 8 is a side view of a portion of a bit body with a PDC cuttingelement attached thereto according to an embodiment of the presentdisclosure.

FIG. 9 is a side view of another portion of a bit body with a PDCelement attached to the bit body without a separate substrate accordingto a method of the present disclosure.

DETAILED DESCRIPTION

The illustrations presented herein are not meant to be actual views ofany particular material, apparatus, system, or method, but are merelyidealized representations which are employed to describe certainembodiments of the present invention.

As used herein, the term “substantially” includes to a degree that oneskilled in the art would understand the given parameter, property, orcondition is met with a small degree of variance, such as withinacceptable manufacturing tolerances.

A method of attaching a polycrystalline diamond compact (“PDC”) elementto a substrate is shown by way of example in FIGS. 4A-4C. Such a methodmay be useful in forming PDC cutting elements including PDC cuttingelements for earth-boring tools.

As illustrated in FIGS. 4A-4C, embodiments of the present disclosureinclude methods of forming a PDC cutting element 150 that includes a PDCelement 100 and a substrate 110 held together by an adhesive material130. The PDC element 100 may be attached to the substrate 110 bypositioning the PDC element 100 and the substrate 110 a distance 105apart from one another to form a gap 120 therebetween, and by fillingthe gap 120 with the adhesive material 130 using a deposition process,as explained below. As shown in FIG. 4A, opposing surfaces of the PDCelement 100 and of the substrate 110 may face the gap 120. The gap 120may be defined by a substantially uniform or a variable distance 105between the PDC element 100 and the substrate 110, depending on theshape of the opposing surfaces. The gap 120 may be maintained by one ormore standoff structures positioned between the PDC element 100 and thesubstrate 110, although other methods of maintaining the gap 120 may beused. In some embodiments, a point or portion of the PDC element 100 maycontact a point or portion of the substrate 110, as shown in FIG. 4A.

The distance 105 between the PDC element 100 and the substrate 110 maybe a relatively small distance to allow a subsequent deposition processto substantially fill the gap 120 with an adhesion material 130, as willbe described in more detail below with reference to FIGS. 4B and 4C. Asnoted above, the distance 105 may be substantially uniform or may varyacross opposing surfaces of the PDC element 100 and the substrate 110facing the gap 120. By way of example and not limitation, a maximumdistance 105 may be between about 1 μm and about 160 μm. In someembodiments, the maximum distance 105 may be between about 60 μm andabout 80 μm. In other embodiments, the maximum distance 105 may bebetween about 120 μm and about 160 μm. Some processes used to form anadhesion material 130 may form a thin film of the adhesion material 130on a surface of the substrate 110 and on a surface of the PDC element100. Such a thin film formed on a single substrate surface may have athickness of up to about 80 μm. Therefore, in such embodiments, themaximum distance 105 may be less than about 160 μm (i.e., twice thethickness to which the thin film may be deposited on each of the surfaceof the substrate 110 and the surface of the PDC element 100 facing thegap 120) to enable such thin films of the adhesion material 130 tosubstantially fill the gap 120. However, other processes may be capableof filling a larger gap. Accordingly, the present disclosure includesembodiments in which the gap 120 is defined by a distance 105 that islarger than the values listed above. The distance 105 may be heldconstant during the formation of the adhesion material 130. For example,standoffs may be used to hold the PDC element 100 adjacent to thesubstrate 110 and the desired distance 105 apart.

In an embodiment in which the distance 105 varies across the surfaces ofthe PDC element 100 and the substrate 110 facing the gap 120, thedistance 105 in a central region of the gap 120 may be smaller than thedistance 105 in an outer region of the gap 120. This variable distance105 may be accomplished by forming the PDC element 100 and/or thesubstrate 110 to have a tapered (e.g., conical, frustoconical, curved,etc.) surface facing the gap 120. In other words, one or more of the PDCelement 100 and the substrate 110 may have a greater thickness in acentral region thereof compared to a thickness in an outer regionthereof. Thus, the gap 120 may be defined by a greater distance 105 inan outer region thereof and by a lesser distance 105 in a central regionthereof. In some embodiments, a surface or point in the central regionof the PDC element 100 may touch the underlying substrate 110,essentially dropping the distance 105 to zero in the central region. Thevariable distance 105 may enable the adhesion material 130 (FIGS. 4B and4C) to fill the gap 120 starting proximate the central region of the gap120 and continuing outwards to the outer region of the gap 120 as thematerial is deposited, thus avoiding or reducing the formation of voidsin the adhesion material 130. For example, the film of adhesion material130 formed in the gap 120 and on the surfaces of the PDC element 100 andof the substrate 110 may be formed (e.g., deposited, grown, etc.) on thesurfaces at a generally uniform rate. However, since the central regionof the gap 120 may be narrower than the outer region, the films on eachof the surfaces of the PDC element 100 and the substrate 110 facing thegap 120 may grow into and contact each other starting at the centralregion and progressing to the outer region, effectively filling the gap120 progressively from the central region to the outer region of the gap120. In this manner, the adhesion material 130 may substantially fillthe entire gap 120 with reduced or substantially no voids, to provide abond across the interface between the PDC element 100 and the substrate110.

Although FIGS. 4A-4C show the PDC element 100 and the substrate 110 bothhaving tapered surfaces facing the gap 120, the present disclosure isnot so limited. For example, one of the PDC element 100 and thesubstrate 110 may have a substantially planar surface facing the gap120. In one embodiment, each of the PDC element 100 and the substrate110 may have a substantially planar surface facing the gap 120.

It is noted that the gap 120, the distance 105, and the slope of thetapering of the surface of the PDC element 100 and of the surface of thesubstrate 110 facing the gap 120 are exaggerated for clarity andconvenience in FIGS. 4A-4C, as well as in FIGS. 5, 6, 8, and 9, whichare described in more detail below. In reality, the gap 120 may besmaller, the distance 105 may be less, and the slope of the tapering maybe lower than is shown in the views of FIGS. 4A-6, 8, and 9.

The PDC element 100 may be a PDC table formed by known methods, such asby a high temperature/high pressure (“HTHP”) method using a diamondpress to form direct diamond-to-diamond inter-granular bonds betweendiamond crystals. In some embodiments, the PDC element 100 may be formedusing a plurality of diamond crystals and a catalyst material toencourage diamond-to-diamond bonding. The catalyst material may be, forexample, silicon, cobalt, iron, nickel, or alloys and mixtures thereof.In one embodiment, the catalyst material may be silicon. In someembodiments, the catalyst material used in the formation of the PDCelement 100 may remain in interstitial spaces between diamond grains ofthe final PDC element 100 used to form the PDC cutting element 150. Inother embodiments, at least a portion of the catalyst material may beremoved (e.g., leached) from the PDC element 100 prior to or afterattaching the PDC element 100 to the substrate 110. For example,catalyst material may be removed from interstitial spaces betweendiamond grains of the PDC element 100 in an outer portion thereof (e.g.,within about 100 μm from an outer surface of the PDC element 100), suchas by dissolving the catalyst material in an acid solution for acontrolled period of time. By way of another example and not limitation,a larger portion (e.g., greater than about 100 μm from an outer surfaceof the PDC element 100) of the catalyst material may be removed frominterstitial spaces between diamond grains of the PDC element 100, suchas by dissolving the catalyst material in an acid solution for a longerperiod of time, while a smaller portion of the catalyst material mayremain in the PDC element 100 compared to thin leaching. In someembodiments, at least substantially all of the catalyst material may beremoved from the PDC element 100. PDC elements with some or all of thecatalyst material removed may be referred to in the art as thermallystable polycrystalline (TSP) diamond elements due to their resistance tothermal and mechanical degradation at relatively higher temperaturescompared to PDC elements with catalyst material remaining ininterstitial spaces between diamond grains throughout the PDC elements.

The substrate 110 may include, by way of non-limiting example, a carbidematerial. For example, the substrate 110 may be formed of aceramic-metallic composite material (i.e., a so-called “cement”material), which may include a plurality of ceramic hard phase particles(e.g., a particulate carbide material) bound together in a metal matrixmaterial. For example, the substrate 110 may comprise cobalt-cementedtungsten carbide. In addition or alternatively, the substrate 110 may beformed of another material with relatively higher toughness to supportthe PDC element 100 attached thereto during drilling of a formation. Thesubstrate 110 may be formed by known methods separately from the PDCelement 100, such as by pressing and sintering granular ceramic materialand matrix material, or by infiltrating a particulate ceramic materialwith a molten matrix material, for example. The substrate 110 may be acemented carbide substrate.

Although the PDC cutting element 150 and the corresponding PDC element100 and substrate 110 are shown as having a generally cylindrical shape,the present disclosure may also apply to cutting elements of other knownor unknown shapes. For example, the cutting element 150 may bedome-tipped, chisel-shaped, tombstone-shaped, etc.

As shown in FIGS. 4B and 4C, the adhesion material 130 may be providedin the gap 120 between the PDC element 100 and the substrate 110. Someexample adhesion materials 130 that may be used in the methods of thepresent disclosure may be a relatively hard material, such as one ormore of diamond (e.g., polycrystalline or monocrystalline diamond),diamond-like carbon (“DLC”), a carbide material (e.g., metal carbide,silicon carbide, etc.), a nitride material (e.g., titanium nitride), anda cubic boron nitride (“CBN”) material. In some embodiments, theadhesion material 130 may be a catalyst material selected to catalyzeformation of inter-granular bonds in diamond material, such as cobalt,iron, nickel, silicon, or alloys and mixtures thereof. The adhesionmaterial 130 may be formed (e.g., deposited, grown) on the surface ofthe PDC element 100 and on the surface of the substrate 110 facing thegap 120. In some embodiments, the adhesion material 130 may fill the gapbeginning in a central region of the gap 120 and proceed outward tosubstantially fill the entire gap 120. By way of example, the initialformation of the adhesion material 130 in a central region of the gap120 may be accomplished by forming one or more of the surfaces of thePDC element 100 and of the substrate 110 to have a non-planarconfiguration, as described above. In addition or as an alternative, oneor more of the surfaces of the PDC element 100 and of the substrate 110may be roughened or textured in an effort to improve the strength of thebond.

The gap 120 between the PDC element 100 and the substrate 110 may befilled with the adhesion material 130 using a deposition process. Inother words, a deposition process may be used to deposit the adhesionmaterial 130 in the gap 120. The deposition process may comprise, forexample, at least one of a chemical vapor deposition (CVD) process, aplasma deposition process, and a physical vapor deposition (PVD)process. In some embodiments, the deposition process may comprise aplasma-enhanced chemical vapor deposition (“PECVD”) process. Plasma arcdeposition processes may also be employed. The deposition process may beperformed at reduced pressure, ambient pressure, or elevated pressure,depending on the technique used and the material to be deposited. Theparticular technique used to form the adhesion material 130 may be afunction of the material used for the adhesion material 130. Forexample, if the adhesion material 130 is to comprise a carbide (e.g.,tungsten carbide) material, a PECVD process using a plasma formed ofions from the carbide material (e.g., tungsten ions and carbon ions) maybe used to deposit the carbide material in the gap 120. By way ofanother non-limiting example, a CVD process using a carbon (e.g.,hydrocarbon) precursor may be used to deposit a diamond or diamond-likematerial in the gap 120.

In some embodiments, the deposition process may be carried out atrelatively low temperatures. For example, the deposition process may becarried out at temperatures below about 600° C., below about 400° C.,below about 200° C., or even below about 150° C.

To form the adhesion material 130 in the gap 120, a plasma depositionprocess may be used. By way of example, a plasma-enhanced chemical vapordeposition (“PECVD”) process may be performed on the PDC element 100 andthe substrate 110 while they are held adjacent one another to form thegap 120. The PECVD process may be performed on the PDC element 100 andthe substrate 110 while disposed within a PECVD chamber, as is known inthe art. Formation of the adhesion material 130 may be accomplished by alow temperature PECVD process. For example, the adhesion material 130may be formed with a process operating at less than about 600° C. Insome embodiments, the adhesion material 130 may be formed with a processoperating at less than about 150° C. In one embodiment, the adhesionmaterial 130 may be formed with a process operating at between about100° C. and about 110° C. The operating temperature of the process usedto form the adhesion material 130 may be less than the temperatures usedin a conventional HTHP process (i.e., above about 1200° C.). Theoperating temperature of the process used to form the adhesion material130 may also be less than the temperatures used to conventionally brazea PDC and a substrate together (e.g., above about 800° C.). Thus, atleast some of the disadvantages of a conventional HTHP process or aconventional brazing process associated with subjecting components of aPDC cutting element to relatively high temperatures may be reduced oravoided by using methods of the present disclosure.

As noted above, in some embodiments, a plasma deposition (e.g., PECVD)process may be used to deposit the adhesion material 130 in the gap 120.For example, HARDIDE® is a tungsten carbide material that may be used asthe adhesion material 130 formed by a plasma deposition process. TheHARDIDE® may be a tungsten carbide material that is vapor deposited at atemperature between about 500° C. and about 600° C. By way of example,methods used to form a HARDIDE® material are disclosed in U.S. patentapplication Ser. No. 09/913,324, filed Feb. 11, 1999, now U.S. Pat. No.6,800,383, titled “TUNGSTEN CARBIDE COATING AND METHOD FOR PRODUCING THESAME,” the disclosure of which is hereby incorporated by referenceherein in its entirety. By way of another example, ADAMANT® diamondcoating is diamond or diamond-like material that may be used as theadhesion material 130 formed by CVD using a carbon precursor and ahydrogen gas mixture. Another method of forming a diamond-like materialthat may be used as the adhesion material 130 is disclosed in PCTPublication No. WO 2008/099220, filed Feb. 15, 2008, and titled “Methodsand Apparatus for Forming Diamond-like Coatings,” the disclosure ofwhich is incorporated herein in its entirety by this reference. Briefly,the PCT publication discloses a method in which a hydrocarbon gasprecursor may be used to form a diamond-like coating on a substrate,which is positioned in a vacuum chamber. A plasma is formed from thehydrocarbon gas precursor using an anode with an aperture, while thesubstrate acts as a cathode. A magnetic field is maintained in thechamber to direct the plasma toward the substrate and to deposit thediamond-like coating on the substrate. Such a process may be carried outat a temperature of less than 200° C., and/or at a temperature of lessthan 140° C. Other methods and materials that are known in the art maybe used to form the adhesion material 130 in the gap 120.

In some embodiments, optional through holes 125 (shown in FIG. 4B indashed lines) may be provided in one or both of the PDC element 100 andthe substrate 110 for flowing material into the gap 120 to form theadhesion material 130. For example, if present, the number, spacing,size, shape, and position of the through holes 125 may be selected toimprove flow of plasma into regions of the gap 120 that may be narrow orotherwise obstructed. After providing a flow path to the gap 120, thethrough holes 125 may be partially or fully filled with the adhesionmaterial 130 during the deposition process used to filling the gap 120.

Optionally, to form the adhesion material 130 in the gap 120 and avoidforming the adhesion material 130 on other surfaces of the PDC element100 and of the substrate 110, surfaces of the PDC element 100 and of thesubstrate 110 not facing the gap 120 may be masked. By way of example,surfaces where formation of the adhesion material 130 is not desired maybe masked with an aluminum material, such as an aluminum foil, beforethe deposition process is performed. In this manner, deposition of theadhesion material 130 on the masked surfaces of the PDC element 100 andof the substrate 110 can be subsequently removed without removing theadhesion material 130 deposited in the gap 120 where no mask isprovided.

The adhesion material 130 may substantially fill the gap 120 and bondthe PDC element 100 and the substrate 110 together to form a PDC cuttingelement 150, as shown in FIG. 4C. The PDC cutting element 150 mayinclude the substrate 110, the adhesion material 130 formed by adeposition process, as described herein, and the PDC element 100 bondedto the substrate 110 with the adhesion material 130.

Although the surfaces of the PDC element 100 and of the substrate 110facing the gap 120 are shown in FIGS. 4A-4C as smooth, in someembodiments, such surfaces may be textured (e.g., etched, scratched,etc.) to provide increased surface area for improved adhesion.

The method of forming the PDC cutting element 150 shown in FIGS. 4A-4Cand described above may have advantages over conventional methods offorming PDC cutting elements. By way of example and not limitation,attaching the PDC element 100 to the substrate 110 with the adhesionmaterial 130 formed at a relatively low temperature (e.g., lower thanthe conventional HTHP methods and lower than the temperatures employedin brazing processes) may reduce stress (e.g., thermal stress) at aninterface between the PDC element 100 and the substrate 110, which mayreduce or eliminate delamination, early cutter failure, or otherproblems caused by such stress.

Furthermore, the PDC element 100 and the substrate 110 may be formed ofmaterials that have conventionally not adhered well together. In otherwords, the compositions of the PDC element 100 and the substrate 110 maybe designed independently of one another. For example, design parametersof the PDC element 100 may not be affected by the design parameters ofthe substrate 110, such as binder content in the substrate 110, becausethe adhesion material 130 may adhere to each of the PDC element 100 andthe substrate 110 independently. For example, the PDC element 100 may beformed with a silicon catalyst instead of a cobalt catalyst while thesubstrate 110 may be formed with a matrix including cobalt. In addition,the PDC element 100 including a silicon catalyst may exhibit improvedqualities (e.g., hardness) than a PDC element including a conventionalcobalt catalyst because the silicon catalyst may react with carbon fromthe diamond to form silicon carbide, a material that may improve thequalities of the PDC element 100. The adhesion material 130, asdescribed above, may form a bond between the PDC element 100 includingthe silicon catalyst and a substrate 110 including a cobalt matrix thatmay be stronger than bonds formed by conventional methods (e.g.,brazing, pressing). Furthermore, the adhesion material 130 of thepresent disclosure may be used to attach the PDC element 100 tonon-conventional substrates 110 (e.g., substrates made from materialsother than conventional cobalt-cemented tungsten carbide).

Another possible advantage of the method of the present disclosure isthe ability to attach a plurality of PDC elements 100 to a plurality ofsubstrates 110 simultaneously as a batch in a common deposition process,thus saving time, effort, and cost. In other words, each PDC element 100of a plurality of PDC elements 100 may be held adjacent to eachsubstrate 110 of a plurality of substrates 110 and placed together in adeposition chamber. The deposition process may be performed on theplurality of PDC elements 100 and substrates 110 to form a plurality ofPDC cutting elements 150. In some embodiments, a bit body (see FIG. 7)having a plurality of PDC elements 100 positioned adjacent to the bitbody may be placed in a deposition chamber and processed, as describedabove, to attach the plurality of PDC elements 100 to the bit body.

Although particular embodiments of the present disclosure have beendescribed with reference to FIGS. 4A-4C, other embodiments of PDCcutting elements, earth-boring tools, and portions thereof are shown byway of example in FIGS. 5-9.

Referring to FIG. 5, a PDC cutting element 160 may include a substrate110, a first adhesion material 130 a over the substrate 110, a first PDCelement 100 a over the first adhesion material 130 a, a second adhesionmaterial 130 b over the first PDC element 100 a, and a second PDCelement 100 b over the second adhesion material 130 b. Each of the firstadhesion material 130 a and the second adhesion material 130 b may beformed as described above to attach the first PDC element 100 a to thesubstrate 110 and the second PDC element 100 b to the first PDC element100 a, respectively. Thus, the PDC cutting element 160 may include aplurality of PDC elements 100 a, 100 b, providing backup cuttingcapabilities and/or improved cutting abilities compared to PDC cuttingelements including only one PDC element. Although FIG. 5 shows the PDCcutting element 160 including two PDC cutting elements 100 a, 100 b, thepresent disclosure includes PDC cutting elements 160 including more thantwo PDC elements 100.

Referring to FIG. 6, details of another embodiment of the PDC element100, the substrate 110, and the gap 120 are shown. The substrate 110 maybe formed to include a surface facing the gap 120 that is substantiallyplanar. The PDC element 100, on the other hand, may be formed to includea substantially planar cutting surface (i.e., the top surface whenviewed in the perspective of FIG. 6) and a surface facing the gap 120that is not substantially planar across the entire surface. For example,the surface of the PDC element 100 facing the gap 120 may have a centralregion that is tapered to cause the PDC element 100 to be thicker in themiddle compared to an outside portion thereof. In other words, thedistance 105 between the substrate 110 and the PDC element 100 may belower in a central region of the gap 120 than in an outer region of thegap 120. In the outer region of the gap 120, the surface of the PDCelement 100 may be substantially planar, as shown in FIG. 6. Thus,portions of the surface of the PDC element 100 facing the gap 120 may besubstantially planar, while other portions of the surface of the PDCelement facing the gap 120 may be non-planar (e.g., at least one ofconical, curved, tapered, frustoconical, etc.). A portion (e.g., anouter portion) of the surface of the PDC element 100 facing the gap 120may be parallel to the surface of the substrate 110 facing the gap 120,while another portion (e.g., a central portion) may be non-parallel tothe surface of the substrate 110 facing the gap 120. In such anembodiment, the adhesion material 130 formed in the gap 120 may beencouraged to fill the gap 120 starting in a central region thereof andextending to an outer region thereof, reducing or eliminating voids inthe adhesion material 130 and establishing a stronger bond. Furthermore,the substantially planar outer portion of the surface of the PDC element100 facing the gap 120 may enable easier and more physically stablestandoff placement to maintain a desired distance 105 between the PDCelement 100 and the substrate 110.

Referring to FIG. 7, an embodiment of an earth-boring tool 200 of thepresent disclosure is shown. The earth-boring tool 200 may include a bitbody 202 formed of materials and by methods known in the art. In someembodiments, for example, the bit body 202 may be formed by infiltratinga powdered carbide material with a molten matrix material. By way ofanother example, in some embodiments, the bit body 202 may be a pressedand sintered cemented tungsten carbide material, formed by pressing andsintering powdered tungsten carbide with a powdered matrix materialincluding one or more of iron, cobalt, and nickel. Such pressed andsintered cemented tungsten carbide bit bodies are disclosed in U.S.patent application Ser. No. 11/272,439, filed Nov. 10, 2005, now U.S.Pat. No. 7,776,256, titled “EARTH-BORING ROTARY DRILL BITS AND METHODSOF MANUFACTURING EARTH-BORING ROTARY DRILL BITS HAVING PARTICLE-MATRIXCOMPOSITE BIT BODIES,” and U.S. patent application Ser. No. 11/271,153,filed Nov. 10, 2005, now U.S. Pat. No. 7,802,495, titled “METHODS OFFORMING EARTH-BORING ROTARY DRILL BITS,” the disclosure of each of whichis hereby incorporated by reference herein in its entirety. Regardlessof the material used for the bit body 202, the earth-boring tool 200 mayinclude one or more PDC cutting elements 150 (and/or PDC cuttingelements 160, as described above (not shown in FIG. 7)) each including aPDC element 100 attached to a substrate 110 according to methods andstructures disclosed herein.

As shown in FIG. 8, in some embodiments, the one or more PDC cuttingelements 150 may be attached to the bit body 202 by, for example,brazing, welding, pressing, sintering, infiltrating, or otherwiseadhering the one or more PDC cutting elements 150 at least partially ina cutter pocket 230 formed in the bit body 202. In some embodiments, thePDC cutting elements 150 may be bonded to the bit body 202 in the cutterpockets 230 using a deposition process, as described herein. In suchembodiments, the bit body 202 with cutting elements 150 positionedadjacent the cutter pockets 230 may be placed in a reactor and subjectedto a deposition process, as described herein. Thus, adhesion material atleast substantially similar to the adhesion material 130 that bonds thePDC element 100 to the substrate 110 may be deposited between the PDCcutting elements 150 and the cutter pockets 230 of the bit body 202.

In some embodiments, the substrate 110 may be omitted and the PDCelement 100 may be bonded directly to a surface or portion of a bit bodyof an earth-boring tool 200 (e.g., a so-called “drag bit,” a so-called“roller cone bit,” a so-called “impregnated bit,” etc.) using adeposition process, as described herein. In other words, a portion ofthe earth-boring tool 200 may act as a substrate to which the PDCelement 100 may be bonded. For example, as shown in FIG. 9, the bit body202 of the earth-boring tool 200 may be formed to have a surface 235 towhich the PDC element 100 may be attached using the adhesion material130 formed by a deposition process, as described in this disclosure. Inother words, the PDC element 100 may be attached directly to the bitbody 202 of the earth-boring tool 200 using embodiments of methods ofthe present disclosure, without first attaching the PDC element 100 toany other substrate 110 other than the bit body 202 of the earth-boringtool 200.

Referring again to FIG. 9 in conjunction with FIG. 7, in addition oralternatively, the bit body 202 may be formed to include one or more PDCcutting element supports 210. The PDC cutting element supports 210 maybe formed integrally with the bit body 202. One or more PDC elements 100may be attached to the one or more PDC cutting element supports 210 ofthe bit body 202 using methods disclosed herein. For example, the PDCelements 100 may be positioned adjacent to the PDC cutting elementsupports 210 of the bit body 202 and a deposition process, as describedherein, may be performed to form the adhesion material 130 between thePDC elements 100 and the PDC cutting element supports 210. In otherwords, the PDC cutting element supports 210 may be substrates to whichthe PDC elements 100 are attached according to methods of the presentdisclosure. Thus, the earth-boring tool 200 may be formed having cuttingsurfaces (i.e., PDC elements 100) attached to the bit body 202 by theadhesion material 130 described above and without the need for brazing,pressing, infiltrating, or otherwise conventionally adhering the PDCelements 100 to the bit body 202. Such conventional methods of adheringPDC cutting elements to bit bodies may form regions of high stress,weakness, and/or premature failure at the interfaces between the PDCcutting elements and the bit bodies. Thus, methods of the presentdisclosure may be used to avoid such problems associated with previouslyknown methods of bonding PDC cutting elements to bit bodies.

In addition or alternatively, the PDC elements 100 may be attacheddirectly to the bit body 202 according to the methods disclosed hereinin locations lacking a PDC cutting element support 210, such as at aleading edge of a gage region 220, as shown in FIG. 7. Such aconfiguration may enable the earth-boring tool 200 to have increasedcutting abilities, better wear resistance, and/or improved backupcutting abilities as compared to conventional earth-boring tools. Inother embodiments, the PDC elements 100 (without any cutting elementsupport 210) may be attached directly to the bit body 202 atconventional locations, such as in cutting element pockets onrotationally leading ends of blades of the bit body 202.

Additional non-limiting example embodiments of the present disclosureare set forth below.

Embodiment 1

A method of attaching a polycrystalline diamond compact element to asubstrate, the method comprising: positioning a polycrystalline diamondcompact element adjacent a substrate; maintaining a gap between thepolycrystalline diamond compact element and the substrate; and at leastsubstantially filling the gap with an adhesion material using at leastone of a chemical vapor deposition process, a plasma deposition process,a plasma-enhanced chemical vapor deposition process, a plasma arcdeposition process, and a physical vapor deposition process.

Embodiment 2

The method of Embodiment 1, wherein the substrate comprises aparticulate carbide material and a metal matrix material.

Embodiment 3

The method of any one of Embodiments 1 and 2, wherein at leastsubstantially filling the gap comprises subjecting the polycrystallinediamond compact element and the substrate adjacent thereto to a chemicalvapor deposition process.

Embodiment 4

The method of Embodiment 3, wherein subjecting the polycrystallinediamond compact element and the substrate adjacent thereto to a chemicalvapor deposition process comprises subjecting the polycrystallinediamond compact element and the substrate adjacent thereto to a chemicalvapor deposition process operating at a temperature of less than about600° C.

Embodiment 5

The method of Embodiment 4, wherein subjecting the polycrystallinediamond compact element and the substrate adjacent thereto to a chemicalvapor deposition process operating at a temperature of less than about600° C. comprises placing the polycrystalline diamond compact and thesubstrate adjacent thereto in a plasma-enhanced chemical vapordeposition chamber and operating the plasma-enhanced chemical vapordeposition chamber with a maximum temperature of less than about 150° C.

Embodiment 6

The method of any one of Embodiments 1 through 5, wherein at leastsubstantially filing the gap with an adhesion material comprises atleast substantially filling the gap with at least one of a diamondmaterial, a diamond-like carbon material, a cubic boron nitridematerial, a carbide material, and a nitride material.

Embodiment 7

The method of any one of Embodiments 1 through 6, further comprisingmasking surfaces of the polycrystalline diamond compact element and ofthe substrate outside the gap to reduce formation of the adhesionmaterial on surfaces outside the gap.

Embodiment 8

The method of Embodiment 7, wherein masking surfaces comprisespositioning an aluminum material over the surfaces.

Embodiment 9

The method of any one of Embodiments 1 through 8, wherein the substratecomprises at least one of a cemented carbide material and a portion of abit body.

Embodiment 10

The method of any one of Embodiments 1 through 9, further comprisingforming the polycrystalline diamond compact element to include a siliconcatalyst.

Embodiment 11

The method of any one of Embodiments 1 through 10, wherein a distancebetween the polycrystalline diamond compact element and the substratedefining the gap is smaller in a central region of the gap than in anouter region of the gap.

Embodiment 12

The method of any one of embodiments 1 through 11, wherein positioning apolycrystalline diamond compact element adjacent a substrate comprisestouching a surface or point of the substrate with a surface or point ofthe polycrystalline diamond compact element.

Embodiment 13

A method of forming a cutting element for an earth-boring tool, themethod comprising: forming a polycrystalline diamond compact element bypressing diamond crystals together; forming a substrate comprising aparticulate carbide material and a matrix material; positioning thepolycrystalline diamond compact element adjacent the substrate leaving agap between at least portions of the polycrystalline diamond compactelement and the substrate; masking surfaces of the polycrystallinediamond compact element and surfaces of the substrate that do not facethe gap; and forming an adhesion material on a surface of thepolycrystalline diamond compact and on a surface of the substrate thatface the gap to at least substantially fill the gap with the adhesionmaterial.

Embodiment 14

The method of Embodiment 13, wherein forming an adhesion materialcomprises forming the adhesion material by at least one of growing anddepositing the adhesion material with a low temperature depositionprocess.

Embodiment 15

The method of Embodiment 14, wherein forming the adhesion material by atleast one of growing and depositing the adhesion material with a lowtemperature deposition process comprises forming the adhesion materialby at least one of growing and depositing the adhesion material with adeposition process at a maximum temperature of less than about 600° C.

Embodiment 16

The method of any one of Embodiments 13 through 15, further comprising:forming another polycrystalline diamond compact element; positioning theanother polycrystalline diamond compact element adjacent thepolycrystalline diamond compact element; and forming another adhesionmaterial between the another polycrystalline diamond compact element andthe polycrystalline diamond compact element by at least one of growingand depositing the another adhesion material with a low temperaturedeposition process.

Embodiment 17

The method of any one of Embodiments 13 through 16, wherein forming anadhesion material comprises forming at least one of a diamond material,a diamond-like carbon material, a cubic boron nitride material, acarbide material, a nitride material, and a catalyst material selectedto catalyze formation of inter-granular bonds in diamond material.

Embodiment 18

The method of any one of Embodiments 13 through 17, wherein forming anadhesion material comprises using a deposition process selected from thegroup consisting of a chemical vapor deposition process, a plasmadeposition process, a plasma-enhanced chemical vapor deposition process,a plasma arc deposition process, and a physical vapor depositionprocess.

Embodiment 19

A cutting element for an earth-boring tool, the cutting elementcomprising: a polycrystalline diamond compact element attached to asubstrate with an adhesion material, the adhesion material formed by adeposition process and comprising at least one of diamond, diamond-likecarbon, a carbide material, a nitride material, and a cubic boronnitride material.

Embodiment 20

The cutting element of Embodiment 19, further comprising anotherpolycrystalline diamond compact element and another adhesion material,the another polycrystalline diamond compact element attached to thepolycrystalline diamond compact element with the another adhesionmaterial

Embodiment 21

The cutting element of any one of Embodiments 19 and 20, wherein thepolycrystalline diamond compact element comprises a silicon material ininterstitial spaces between grains of diamond of the polycrystallinediamond compact element.

Embodiment 22

The cutting element of any one of Embodiments 19 through 21, wherein thepolycrystalline diamond compact element is formed by forminginter-granular diamond bonds in the presence of a catalyst material andremoving at least a portion of the catalyst material from interstitialspaces between grains of the polycrystalline diamond compact.

Embodiment 23

A method of forming an earth-boring tool, the method comprising: forminga bit body of an earth-boring tool; forming a polycrystalline diamondcompact element; and attaching the polycrystalline diamond compactelement to the bit body, the attaching comprising: positioning thepolycrystalline diamond compact element adjacent an outer surface of thebit body such that a gap remains between at least portions of thepolycrystalline diamond compact element and the outer surface of the bitbody; and providing an adhesion material in the gap between thepolycrystalline diamond compact element and the substrate by adeposition process.

Embodiment 24

A method of forming an earth-boring tool, the method comprising: forminga bit body of an earth-boring tool; forming a polycrystalline diamondcompact element; forming a substrate configured to support thepolycrystalline diamond compact element; attaching the polycrystallinediamond compact element to the substrate to form a cutting element, theattaching comprising; positioning the polycrystalline diamond compactelement proximate the substrate such that a gap remains between at leastportions of the polycrystalline diamond compact element and thesubstrate; and providing an adhesion material in the gap between thepolycrystalline diamond compact element and the substrate by adeposition process; and attaching the cutting element to an outersurface of the bit body.

Embodiment 25

An earth-boring tool for drilling subterranean formations, theearth-boring tool comprising: a bit body; a polycrystalline diamondcompact attached to the bit body; and an adhesion material comprising atleast one of diamond, diamond-like carbon, a carbide material, a nitridematerial, and a cubic boron nitride material, the adhesion materialdisposed between and in contact with the polycrystalline diamond compactand the bit body.

While the present invention has been described herein with respect tocertain embodiments, those skilled in the art will recognize andappreciate that it is not so limited. Rather, many additions, deletions,and modifications to the embodiments depicted and described herein maybe made without departing from the scope of the invention as hereinafterclaimed, and legal equivalents of the invention. In addition, featuresfrom one embodiment may be combined with features of another embodimentwhile still being encompassed within the scope of the invention ascontemplated by the inventor. Furthermore, the invention has utility inconjunction with earth-boring drill bits having different bit profilesas well as different cutter types. For example, methods and structuresof this disclosure may find use with any type of earth-boring tool, suchas a drag bit, a roller cone bit, an impregnated bit, a hybrid bit, anda core bit.

What is claimed is:
 1. A method of attaching a polycrystalline diamondcompact element to a substrate, the method comprising: positioning apolycrystalline diamond compact element adjacent a substrate;maintaining a gap between the polycrystalline diamond compact elementand the substrate; and at least substantially filling the gap with anadhesion material using at least one of a chemical vapor depositionprocess, a plasma deposition process, a plasma-enhanced chemical vapordeposition process, a plasma arc deposition process, and a physicalvapor deposition process.
 2. The method of claim 1, further comprisingforming the substrate to include a particulate carbide material and ametal matrix material.
 3. The method of claim 1, wherein at leastsubstantially filling the gap comprises subjecting the polycrystallinediamond compact element and the substrate adjacent thereto to a chemicalvapor deposition process.
 4. The method of claim 3, wherein subjectingthe polycrystalline diamond compact element and the substrate adjacentthereto to a chemical vapor deposition process comprises subjecting thepolycrystalline diamond compact element and the substrate adjacentthereto to a chemical vapor deposition process operating at atemperature of less than about 600° C.
 5. The method of claim 4, whereinsubjecting the polycrystalline diamond compact element and the substrateadjacent thereto to a chemical vapor deposition process operating at atemperature of less than about 600° C. comprises placing thepolycrystalline diamond compact and the substrate adjacent thereto in aplasma-enhanced chemical vapor deposition chamber and operating theplasma-enhanced chemical vapor deposition chamber with a maximumtemperature of less than about 150° C.
 6. The method of claim 1, whereinat least substantially filing the gap with an adhesion materialcomprises at least substantially filling the gap with at least one of adiamond material, a diamond-like carbon material, a cubic boron nitridematerial, a carbide material, and a nitride material.
 7. The method ofclaim 1, further comprising masking surfaces of the polycrystallinediamond compact element and of the substrate outside the gap to reduceformation of the adhesion material on surfaces outside the gap.
 8. Themethod of claim 7, wherein masking surfaces comprises positioning analuminum material over the surfaces.
 9. The method of claim 1, furthercomprising forming the substrate to include at least one of a cementedcarbide material and a portion of a bit body.
 10. The method of claim 1,further comprising forming the polycrystalline diamond compact elementto include a silicon catalyst.
 11. The method of claim 1, furthercomprising maintaining a distance between the polycrystalline diamondcompact element and the substrate to be smaller in a central region ofthe gap than in an outer region of the gap.
 12. The method of claim 1,wherein positioning a polycrystalline diamond compact element adjacent asubstrate comprises touching a surface or point of the substrate with asurface or point of the polycrystalline diamond compact element.
 13. Themethod of claim 1, wherein at least substantially filling the gap withan adhesion material comprises forming the adhesion material on asurface of the polycrystalline diamond compact facing the gap.
 14. Themethod of claim 1, further comprising providing through holes in atleast one of the polycrystalline diamond compact and the substrate andat least partially filling the through holes with the adhesion material.15. A method of forming a cutting element for an earth-boring tool, themethod comprising: forming a polycrystalline diamond compact element bysintering and bonding diamond crystals together; forming a substratecomprising a particulate carbide material and a matrix material;positioning the polycrystalline diamond compact element adjacent thesubstrate leaving a gap between at least portions of the polycrystallinediamond compact element and the substrate; masking surfaces of thepolycrystalline diamond compact element and surfaces of the substratethat do not face the gap; and forming an adhesion material on a surfaceof the polycrystalline diamond compact and on a surface of the substratethat face the gap to at least substantially fill the gap with theadhesion material.
 16. The method of claim 15, wherein forming anadhesion material comprises forming the adhesion material by at leastone of growing and depositing the adhesion material with a lowtemperature deposition process.
 17. The method of claim 16, whereinforming the adhesion material by at least one of growing and depositingthe adhesion material with a low temperature deposition processcomprises forming the adhesion material by at least one of growing anddepositing the adhesion material with a deposition process at a maximumtemperature of less than about 600° C.
 18. The method of claim 15,further comprising: forming another polycrystalline diamond compactelement; positioning the another polycrystalline diamond compact elementadjacent the polycrystalline diamond compact element; and forminganother adhesion material between the another polycrystalline diamondcompact element and the polycrystalline diamond compact element by atleast one of growing and depositing the another adhesion material with alow temperature deposition process.
 19. The method of claim 15, whereinforming an adhesion material comprises forming at least one of a diamondmaterial, a diamond-like carbon material, a cubic boron nitridematerial, a carbide material, a nitride material, and a catalystmaterial selected to catalyze formation of inter-granular bonds indiamond material.
 20. The method of claim 15, wherein forming anadhesion material comprises using a deposition process selected from thegroup consisting of a chemical vapor deposition process, a plasmadeposition process, a plasma-enhanced chemical vapor deposition process,a plasma arc deposition process, and a physical vapor depositionprocess.